Boiler not working? Get your heating fixed
No heat from your boiler or cold radiators? Run a few safe checks below, then call us to book a Gas Safe registered engineer.
Boiler not working? Start here
A boiler not working in the middle of winter is no fun, but you're in the right place. Before you book anyone out, there are a few safe checks you can do yourself that often get the heating going again. If those don't sort it, call us on 0333 772 6247 and we'll send a Gas Safe registered engineer to find the fault and fix it.
Smart Plan is a service plan, not insurance — and you don't need a plan to book a one-off repair.
Why is my central heating not working?
Cold radiators, boiler no heat, or central heating not working at all usually comes down to one of a handful of common causes. Some you can check in a couple of minutes — a thermostat that's been knocked off, a boiler left on hot-water-only mode after summer, low pressure, or a radiator valve that's still shut. Others, like a stuck diverter valve or sludge in the system, sit inside the sealed boiler casing and need a Gas Safe registered engineer.
Smell gas or worried about carbon monoxide? Stop here
If you can smell gas, hear hissing near the boiler or pipework, or your carbon monoxide alarm is going off, don't try any checks. Turn the gas off at the meter if it's safe to, open windows, leave the property and call the National Gas Emergency line on 0800 111 999. Only go back in once you've been told it's safe.
Safe checks you can try yourself
These are the only checks a homeowner should do. Don't open the boiler casing or touch any internal parts — that's always a job for a Gas Safe registered engineer.
Quick troubleshooting checklist
| Check | What to do | Why it helps |
|---|---|---|
| Power and gas supply | Check the boiler hasn't tripped a switch at the fuse box, the plug or spur is on, and you've got credit if you're on a prepayment meter. | No power or no gas means the boiler simply can't fire. |
| Thermostat | Turn it up to about 21°C and make sure the timer or programmer is set to come on. | Heating won't fire if the set temperature is lower than the room, or the timer is off. |
| Hot water vs heating mode | Check the boiler isn't set to hot water only — a common setting left over from summer. | Many boilers can run hot water without the central heating. |
| Boiler pressure | Look at the pressure gauge. If it's below about 1 bar, top it up using the filling loop as shown in your boiler manual. | Low pressure stops hot water circulating to the radiators. |
| Radiator valves | Make sure the valves at each end of your radiators are open. | A valve turned off over summer leaves that radiator cold. |
| Reset the boiler | Press the reset button only if and as your boiler manual tells you to. | A single reset can clear a one-off lockout. |
When to stop and book an engineer
- You've run the checks above and there's still no heating.
- The boiler shows a fault or lockout code that the manual says needs an engineer.
- The boiler keeps losing pressure or needs topping up again and again.
- You've got hot water but the heating still won't come on (this can be a stuck diverter or motorised valve, which sits inside the boiler).
- There's water leaking from the boiler or pipework, or you can hear gurgling and banging from the system.
How a one-off repair works
How a one-off repair works
If the safe checks don't fix it, call us on 0333 772 6247 to book a one-off repair. One-off repair visits run Monday to Friday, 09:00 to 17:00. A £95.00 call-out fee applies and is paid in advance. The engineer will diagnose the fault and tell you what's needed before any work goes ahead.
A one-off repair is a paid, pay-per-visit service and carries no workmanship guarantee. If you'd rather have your boiler and heating covered going forward, you can build a Smart Plan instead — see below.
Already worried it'll happen again? Build cover
Smart Plan is a service plan, not insurance. You pick only the modules you want, and the boiler & central heating module covers parts and labour up to £500 if your boiler is under 7 years old, or £200 if it's over 7 years old, per 12-month period. It runs as monthly rolling cover, though once you've used a service a 12-month agreement period applies, and leaving early means paying the remaining months or 75% of the outstanding balance. The phone repair above is the quickest route today; cover is the smart way to handle the next time.
Need it fixed today?
Call 0333 772 6247 to book a Gas Safe registered engineer. One-off repairs Mon-Fri 09:00-17:00, £95 call-out paid in advance.
Boiler not working: common questions
Why is my boiler not working but I still have hot water?
If you've got hot water but no heating, the boiler is often set to hot water only, the thermostat or timer is off, the radiator valves are closed, or the pressure is low. Try those checks first. If they don't help, a stuck diverter or motorised valve inside the boiler may be to blame — that's a job for a Gas Safe registered engineer.
Why are my radiators cold when the heating is on?
Cold radiators usually mean a closed valve, trapped air, low boiler pressure, or sludge build-up in the system. Check the valves are open and the pressure is around 1 to 1.5 bar. If the radiators stay cold, book an engineer to look at the system.
Can I fix my boiler myself?
You can safely check the power and gas supply, the thermostat, the boiler pressure, the radiator valves, and press the reset button if your manual says to. You should never open the boiler casing or touch internal parts. Anything inside the boiler must be done by a Gas Safe registered engineer.
What should I do if I smell gas?
Don't run any checks. Turn the gas off at the meter if it's safe, open windows, leave the property, and call the National Gas Emergency line on 0800 111 999. Only return once you've been told it's safe.
How much does a one-off boiler repair cost?
A one-off repair visit carries a £95.00 call-out fee, paid in advance. The engineer diagnoses the fault and tells you what's needed before any further work goes ahead. One-off visits run Monday to Friday, 09:00 to 17:00. A one-off repair is a paid, pay-per-visit service and carries no workmanship guarantee.
Why does my boiler keep losing pressure?
If the pressure drops again soon after you top it up, that usually points to a leak in the system or a faulty part such as the pressure relief valve or expansion vessel. That's not a homeowner fix, so book a Gas Safe registered engineer to find and repair the cause.
Do I need a cover plan to book a repair?
No. You can call us for a one-off repair whenever you need one, with a £95 call-out fee. A Smart Plan cover plan is optional and may suit you if you'd rather spread the cost and help protect against future repair bills.
Call us today
Customer service
0333 772 6247New customers
0333 772 6247Write to us
By email
hello@smart-plan.comBy post
2nd Floor, Melrose House
42 Dingwall Road
Croydon
CR0 2NE